Pulse detonation jet propulsion



6 Sheets-Sheet 1 Filed Sept. 30. 1952 N m ON m:

. /-m w W 6m mm? mm mm i 1 mm mm mm WILLIAM BOLLAY,

INVENTOR.

BY JQ ATTORNEY June 28, 1960 w. BQLLAY 2,942,412

PULSE DETONATION JET PROPULSION Filed Sept. 30. 1952 6 Sheets-Sheet 2 WILLIAM BOLLAY,

INVENTOR.

ATTORNEY June 28, 1960 2 w. BOLLAY 2,942,412

PULSE DETONATION JET PROPULSION Filed Sept. 30. 1952 6 Sheets-Sheet 3 WILLIAM BOLLAY,

INVENTOR.

ATTORNEY 6 Sheets-Sheet 4 Filed Sept. 30, 1952 WILLIAM BOLLAY,

INVENTOR.

ATTORNEY June 28, 1960 w. BOLLAY 2,942,412

PULSE DETONATION JET PROPULSION Filed Sept. 30. 1952 6 Sheets-Sheet 5 FIG. 6.

WILLIAM BOLLAY,

INVENTOR.

ATTORNEY June 28, 1960 w. BOLLAY 2,942,412

PULSE DETONATION JET PROPULSION Filed Sept, 30, 1952 6 SheetsSheet 6 FIG. 9.

FIG. 10.

WILLIAM BOLLAY,

INVENTOR.

ATTORNEY cules.

United States Patent PULSE DETONATION JET PROPULSION William Bollay, Pacific Palisades, Calif., assign0r, by mesne assignments, to Curtiss-Wright Corporation, a corporation of Delaware Filed Sept. 30, 1952, ser. No. 312,327 Claims. ((11. 6035.6)

This invention relates to jet propulsion by means of fuel detonation.

A number of forms of jet propulsion are known including rocket, ramjet,-turbojet and pulse jet engines. This invention relates to a new form of jet engine and takes advantage of the high energy and power developed from fuel, for example, a petroleum hydrocarbon fuel such as a jet turbine fuel, which, mixed with air is detonated at constant volume and preferably also of compression of a new fuel charge before detonation by means of a shock wave. A detonation wave is the propagation of a front of chemical reaction of a mixture of gas moving through the mixture at extremely high velocity, for example, such as 8,000 feet per second, in-

, volving at the front a discontinuous temperature and pressure rise, that is, an abrupt increase in temperature and pressure in an exceedingly small distance of the order of magnitude of the mean free path of the mole- Primarily because of the utilization of detonation of fuel for very rapid combustion at constant volume in the apparatus and method of my invention, it is to be distinguished from what is ordinarily known as the pulse jet engine. However, the engine of this invention is a new form of pulse jet, but is importantly different so as to constitute a new kind of pulse jet having many important advantages over the known pulse jet engine, particularly in that it has a much higher efficiency. The jet pulses delivered from the engine of this invention also constitute a source of high energy sound waves, the frequency of which may be controlled, and thus the engine may be operated to produce high energy ultrasonic sound waves.

In accordance with the invention, detonation of'a fuel is caused to takeplace in a confined enclosure such as a tube. The resulting high temperature gases at high pressure blow out the open end of a tube as a jet and the reaction causes a thrust against the opposite closed end of the tube. This thrust provides the power of the engine of this invention.

It is a further feature of this invention that the detonation of fuel within the tube is initiated by a shock wave produced within the tube, preferably at the outlet end thereof, which shock wave travels upstream and impinges against and is reflected by the closed end of the tube, raising pressure and temperature sufficiently high to initiate the detonation wave in the tube traveling from the closed end to the open outlet end thereof. A shock wave is a traveling front through which pressure and temperature rise discontinuously, that is, increase abruptly in an exceedingly minute distance of the order of magnitude of the mean free path of the molecules. In a shock wave the velocity of the traveling front is greater than the speed of sound and it raises the pressure and temperature of the gases through which it traverses. The shock wave here referred to is to be distinguished from a sound wave and from an expansion wave,

It is an important feature and advantage in accordance with the invention that the pressure increase obtained heavier.

in a tube by using the combination of a shock wave and detonation is a surprisingly large increase in a very short period of time, especially because the detonation increases the pressure already having been increased by the shock wave, so that the resulting total pressure increase is exceedingly high. For example, the. shock wave may increase this pressure by 'a factor of two, and the detonation may increase this increased pressure by a factor of five so that the resulting total pressure increase is such that the resulting pressure is ten times the original pressure and this pressure increase can be obtained for a large mass of gas in a closed chamber in an exceedingly short time.

Accordingly, it is an object of the invention to provide a jet propulsion engine in which fuel is detonated.

It is another object of the invention to provide such an engine in which the detonation is effected by means of a shock wave and the shock wave and resulting detonation wave cooperate to substantially increase the pressure of the gas in the combustion zone.

It is still a further object of my invention to provide a pulse jet engine having a very simple propulsive system requiring no mechanical compressors or turbines and yet having an efficiency close to that of the turbojet engine, which is much more complex arid much Further important objects and advantages of the invention will be apparent from the disclosure of the invention herein. e

To carry out the necessary steps to provide for the detonation and shock wave, a tube with open ends is provided with means for opening and means for closing the outlet end and inlet end of the tube and with means for introducing fuel, that is, fuel-air mixture, intothe inlet end of the tube. 'In time sequence the'operations involve opening the inlet end of the tube to admit fuel which is passed toward the outlet end at high velocity. When the tube is filled with fuel, a shock wave is caused to travel upstream toward the inlet end. Before this shock wave reaches the inlet end, the inlet opening of the tube is closed so that the shock wave will impinge against and be reflected by the closure at the inlet end causing at the impingement face of the closure a rapid and large increase in pressure and temperature. It is an especially important discovery in accordance with the invention that this impingement and reflection of such a shock wave will not only incr'ease'the pressure of the fuel-air mixture but will also initiate a detonation wave which travels through the fuel-air mixture from the inlet to the outlet of the tube causing a release of a large quantity of energy appearing as gases at very high pressure and very high temperature.

These gases blow out the open end of the tube and thus thrust against the closed end. The inlet end of the tube isv then opened and the gases exhausting at a high velocity suck in fuelair mixture through the inlet and into the tube froma fuel supply means at the proper time.

It is a further important feature of the invention that the shock wave used to initiate the detonation wave may be created by closing the outlet end of thetube to suddenly stop fuel-air gases in their high velocity movement through the tube causing a reflected shock wave to travel back upstream from the outlet to the inlet end of the tube and there impinge on and be reflected by the closed inlet end. It is a. still further prefer-red feature of this invention that the shock wave is formed by turning back a portion of the high pressure gases resulting from detonation into the outlet end of a tube to cause the shock wave to travel upstream therein and initiate detonation as described above. v I I The best arrangement for obtaining jet propulsion in accordance with the invention consists of an assembly of thin walled circular tubes packed longitudinally in a cylinder held together by headers in front and rear. The packing arrangement is preferably such as to obtain as many tubes as" possible in the cylinder. Thetubes are preferably circular incross-section but the cross section may be ashape other than circular. if desired. Two rotating plates each having two cut-outs shapedlike a piece of pie, mounted at the ends of a shaft passing through the center of the cylinder serveas inlet and exhaust valves respectively. Each valve has plates, also shaped like pieces of pie, so arranged that there is a force balance about the center line of rotation, and the size of each diametrically opposed valve plate and cut-out will be such as to provide the proper closure and-opening time; The open cut-out of the inlet valve will. provide the proper time for the inlet of fuel and air to the tubes. The exhaust 'valve plates will close the outlets and the inlet valve plates will close the inlets of the tubes at'the proper time. The cut-outs of the exhaust valve will provide the proper time for exhaust of gases out the outlet end of the tubes. The relation between the exhaust valve and the inlet valve as mounted on the common shaft will be such that the inlet valve will close and open at the proper time in relation to the closing and opening of the exhaust valve so that the exhaust valve will start a shock wave toward the inlet and the inlet valve will close in time to receive this shock wave. This will be described in more detailbelow. In general the cycle of operation will involve the step of introducing fuel-air mixture through the open inlets of a group of tubes which mixture moves down the tubes toward the outlet end thereof. The outlet valve then closes rapidly thus stopping the flow of fuel-air mixture and forming a normal shock wave in the gases which travels forward toward the inlet valve compressing the fuel-air mixture. Upon the arrival of the normal shock wave at the inlet end of the tube, the inlet valve closes and the shock wave impinges against and is reflected by the face of the inlet valve. This shock wave thus initiates detonation, and the resulting detonation wave sweeps through. the fuel-air mixture at high speed, for example, of the order of magnitude of 8,000 feet per second, toward the outlet end. Since the burning occurs in a closed vessel, the desirable conditions of constant volume burning are obtained. The exhaust valve is then opened and thrust is obtained from the jet discharge of the high pressure gases out the back end of the tubes. The inlet valve then opens again, a new fuel-air mixture is introduced, and the burnt gases are scavenged out the rear as fuel is introduced. This cycle is then repeated.

The invention will be illustrated by describing a particular embodiment thereof as shown in the accompanying drawings, in which:

Fig. 1 is a vertical sectional view of the engine of the invention with parts shown in elevation.

. Fig. 2 is a front elevational view of the engine as seen in Fig. 1, with parts broken away.

Fig. 3 is a horizontal sectional view taken on line 3-3 of Fig. 1.

. 4 is a rear elevational view of the engine as seen in Fig. 1, with parts broken away.

Fig. 5 is a sectional view as seen on the arcuate line 5-5 of Fig. 4.

Fig. 6 is a vertical sectional view as seen on line 66 of Fig. 1, omitting the outer housing and detonation chambers.

Fig. 7 is a horizontal sectional view taken on arcuate line 7-7 of Fig. 6. I Fig. 8 is a vertical sectional view taken on line 8-8 of Fig. 1, omitting the outer housing and detonation chambers.

Fig. 9 is a horizontal sectional view as taken on arcuate line 9-9 of Fig. 8.

Fig. 10 is an exploded perspective view showing the I4 relation of cylinder with detonation tubes, inlet valve and fuel headers, and exhaust valve.

Referring to Fig. l, and to the exploded perspective view of Fig. 10, it will be seen that this embodiment of my invention has a set of parallel cylindrical combustion or detonation tubes 35 arranged within a drum-like cylinder 74 having outside cylindrical housing 5, front end wall 45, and back end wall. 46. The tubes 35 are fixed within holes in these two end walls and extend from one wall to the other, each tube being open at both ends. The tubes are arranged in a group of six circles with the tubes on the outer circle having the largest diameter, and gradually decreasing in diameter to the sixth inner circle of tubes of smallest diameter.

Arranged to rotate on the face of the front end wall 45 is inlet valve 25 having two diametrically opposed portions 123 and 124, as shown particularly in Fig. 10, together with two diametrically opposed groups of fuel inlet headers 31, 32 and 33 in one group, and 41, 42 and 43 in the other. Header 31 is diametrically opposite header 43, header 32 diametrically opposite header 42, and header 33 diametrically opposite header 41. Arranged to rotate at the face ofback end wall 46 is exhaust valve 13 also having two diametrically opposed portions 125 and 126 as shown particularly in Fig. 10.

Fuel-air mixture is supplied to the inlet end of the tubes with the fuel under pressure vaporized as it emerges from the orifices 34 of the fuel headers While air enters from the front passing around the fuel headers. This fuel-air mixture passes through the tubes toward the outet end, which is closed at the proper time by the exhaust valve to cause a shock Wave to travel back toward the inlet of the tubes. The inlet valve is closed in time to receive this shock wave, and the shock wave, impinging on the face of the closed inlet valve, initiates a detonation within the tubes. This detonation progresses forwardly at high speed raising the temperature and pressure of the gas to a very high value, and these gases at such high temperature and pressure react against and provide thrust on the face of the inlet valve 25 as they are forced outthe outlet end of the tubes. The continual thrust from the detonation within the tubes reacting or applied against the face of the two diametrically opposed portions of inlet valve 25 is transferred through a thrust bearing to the vehicle or object to which the force is to be applied.

In accordance with the preferred embodiment here illustrated, the'fuel is first preheated by passing in heat exchange with the hottest portions of the engine, particularly including the cylindrical housingv 5, the exhaust valve 13 and the inlet valve 25, to cool these engine parts and also to preheat the fuel. it will be understood, of course, that the fuel could be directly supplied to the fuel inlet headers and that the hot parts of the engine could be cooled by other means, if operating temperatures and the materials used for construction require such cooling.

As shown in Fig. 1, the fuel for the pulse detonation jet engine of this invention, such as a petroleum hydrocarbon jet engine fuel, similar to kerosene, is introduced under pressure by way of inlet pipe 1 into an annular distributing header 2. extending around the circumference of casing 3 and housing 5, from which the fuel passes through an annular port 70 into an annular space 4 between the casing 3 and the cylindrical housing 5 surrounding the set of combustion tubes. Extending between the outside of rousing Sand the inside of casing 3, there is spiral rib 6. This spiral rib holds the housing within the casing and, together with the casing 3 and housing 5, provides a spiral channel about the housing through which the fuel passes spirallyin its course from the front of the housing 5 to the back thereof.

At the back end of the housing 5, annular collecting header 7 extending around the circumference of housing 5 and casing 3, communicates by way of annular port 71, with the annular space 4. The fuel from space 4 passes through port 71 into header 7 and leaves the annular header 7 by way of three ports 8 leading into three hollow struts 9 which join'at a central hollow hub 10 and deliver the fuel to this hub. From hollow hub 10 the fuel passes by way of central passage 11 into passage 12 of rotatable exhaust valve 13. Sealing means 14 is provided for sealing the stationary inlet passage 11 with respect to the rotatable portion of valve 13 forming passage 12.

Each diametrically opposed portion of exhaust valve 13 has hollow channels through which the fuel passes to cool the exhaust valve. As most clearly shown in Fig. 8, hollow portions 15 and 17 are separated by 'rib 68 having port 16 at its outer end providing communication between hollow portions 15 and 17. In the other diametrically opposed half of the exhaust valveare hollow portions 19 and 21 separated by a rib 72 and having a port providing communication between the hollow portions 19 and 21. Port '67 provides communication from passage 12 into hollow portion 15, port 69 (Figs. 1 and 9) provides communication from hollow portion 17 to passage 18 (Fig. 1) leading through the central part of exhaust valve 13 to hollow portion 19 on this half of this valve by way of port 73. Port 74 provides communication from hollow portion 21 into passage 22, also at the central portion of exhaust valve 13, leading into the hollow tube or shaft 23 rotatable with exhaust valve 13. Hence, in accordance with this arrangement the fuel passes through the hollow channels in exhaust valve 13 from passage 12, through port 67, through hollow portion 15, port 16, hollow portion 17, port 69, passage 18, port 73, hollow portion 19, port 20, hollow portion 21, port 74, into passage 22 and thence into hollow shaft 23. In hollow shaft 23, the fuel travels forwardly toward the inlet valve. a

As shown most clearly in Fig. 10, the inlet valve consisting of two diametrically opposed portions 123 and 124, together With the fuel headers on shaft 23, all rotatable as a unit. Shaft 23, at the inlet valve, has ports 74 providing communication from the hollow portion of shaft 23 into central passages 26 and 36 of the inlet valve. As the fuel leaves hollow shaft 23 through the two ports 75, it divides into two streams in the two distributing headers 24. As most clearly seen in Fig. 6, one-half of the inlet valve 25 has hollow portions 27 and 29 separated by rib, 76 with port 28 at the end thereof. Hollow portion 29 has port 30 leading into central distributing head 77 which has openings leading into fuel headers 3-1, 32 and 33.

Thus, on this half of the inlet valve, the fuel enters passage 26 by way of port 75, passes through port 24 into hollow portion 27, through port 28, hollow portion 29', port 30, distributing head 77, and into the fuel headers 31, 32 and 33. The same arrangement is provided on the other half of the inlet valve so that the second stream of fuel passes through port 75, through passage 36, port 24, hollow portion 37, port 38 in rib 78, through hollow portion 39, port 40, distributing head 79 and thence into fuel headers 41, 42 and 43,

Each of the fuel headers has six orifices 34 opening toward the inlet ends of the tubes but directed backwardly at an angle with respect to the direction of rotation of the header over the front face of end wall 45. The centers of these orifices are substantially aligned with the circle passing through the centers of each of the six circles of tubes. The line of orifices for header 31 is on the same diameter as the line of orifices on header 43. This is likewise true for the two headers 32 and 42 and the two headers 33 and 41. The relative size of openings of the orifices distributed along any particular fuel header will be such to provide the desired relative quantity of fuel to the tubes of any of the six circles in accordance with the fuel requirements, taking into account the diameter of the tubes and the pressure along the header varying with the centrifugal force due to rotation of the headers at high speed. Fuel under pressure is forced through the orifices 34 and vaporized as introduced into the combustion tubes 35.

In the embodiment here illustrated, the drum-like cylinder 74 carrying the group of tubes 35 is fixed to casing 3, but the exhaust valve and inlet valve with fuel headers rotate with hollow shaft 23 as a unit. Means are accordingly provided to permit the rotation of shaft 23 within the central portion of cylinder 74. Thus cylinder 74 is mounted on a hollow tube 79 by means of radial ribs 86 with ball bearings 80 and 81 arranged between tube 79 and shaft 23. These two ball bearings 80 and 81 provide an arrangement whereby shaft 23 may rotate within the cylinder 74 rotatably carrying exhaust valve 13 and inlet valve 25 with fuel headers. It will be understood that these ball bearings do not carry the thrust load of the engine, but merely provide for the relative rotation of the group of tubes and the valves and fuel headers.

In order to bring about the rotation of the inlet valve with fuel headers and the exhaust valve, advantage is taken, in accordance with this embodiment of the invention, of the current of air sucked into the inlet of the tubes 35, or impinging on the face of the front of the tubes when the engine is moved through the air. This air current is used by placing a windmill on shaft 47, forward of the shaft 23 in front of the inlet valve at the front of the engine in the current of air entering within the front of easing 3. Thus, at the front end of shaft 47 is hub 48 carrying wheel 82 the outer rim 83 of which carries a series of equally spaced windmill blades 49. Air moving through the front of easing 3 impinging on blades 49 turns them with wheel 82, shaft 47, shaft 23, inlet valve with fuel headers, and exhaust valve 13.

Adjacent blades 49 of this windmill are arranged means for regulating the speed of rotation of the windmill blades. Thus in front of rotatable blades 49 is mounted another set of blades 89 which set is fixed in front of blades 49 and do not rotate as blades 49. Blades 89, however, may be turned about their longitudinal axes to thereby control the angle at which the incoming air current strikes blades 49 to, in turn, control the speed of rotation of blades 49 and hence the speed of rotation of the valve and fuel header assembly. As shown in- Fig. 1 each blade 89 carries a small shaft 91 at its lower endrotatably extending into a hole in a ring 92. The other end of each blade 89 also carriesa shaft 93 rotatably extending through a hole in the flared portion of cylindrical inner wall 87. On the end of each shaft 93 is fixed a small gear 94 so that by turning gears 94, blades 89 may be adjusted to control the speed of rotation of windmill blades 49 and hence the valve and fuel header assembly to control the speed of operation of the engine. v

For the purpose of directing the air stream straight into the open ends of the tubes 35, there is provided another set of blades 95 immediately behind blades49 which re-direct the air flow, after impingement from blades 49, in a direction parallel to the tubes 35, that is, normal to the front end wall 45 of the cylinder 74. Like blades 89, blades 95 do not rotate as do blades 49, but are mounted for adjustment about their longitudinal axes by shafts 96 at their lower ends rotatably extending into holes in cylindrical member 97 fixed to struts 64 and shafts 98 rotatably extending through holes in cylinder 87. Shafts 98 carry fixed gears 99 for adjusting blades 95 to adjust the direction of the air current leaving blades 49 parallel to tubes 35.

Means are also provided for adjusting all of gears 94 and gears 99 together. Between each pair of gears 94 and 99 is a gear 100 fixed to a shaft 117 rotatably extending through a hole in casing 3 and having another gear 118 fixed on the other end thereof. All of gears 118 are engaged by a ring gear extending about the periphery of easing 3. Movement of ring gear 119 causes movement of all gears 118, shafts 117, gears 100, gears 94 and.

blades 89 and gears 99 and blades 95. Hence movement of ring gear 119 effects an adjustment of the speed of rotation of the valve and fuel header assembly and directs the air current straight into the combustion tubes. To move ring gear 119, it may conveniently be provided with gear teeth 120 engaged by gear 121 fixed on shaft 122. Turning of shaft 122 by a motor or handle will then move the ring gear 119 and adjust the speed of the valves of the engine.

In accordance with the preferred embodiment of the invention, the length of the tubes may be inches, the diameter of the cylinder 33 inches (with the diameter of the outer edges of the outer circle of tubes inches). The inside diameters of the circles of tubes from the outer to inner circles may be 2.45, 2.075, 1.75, 1.40, 1.15, and 0.95 inches respectively. The angle of each diametrically opposed portion of the inlet valve is 108 and the angle of each corresponding portion of exhaust valve may be 76. The angular displacement between the front edge of the exhaust valve and the front edge of the inlet valve may be about 23 with the exhaust valve edge ahead of the inlet valve. For a flight speed of the engine through the atmosphere whose Mach number is 2.8 the rotation of the valves will, for example, be 5100 revolutions per minute.

The front and back faces of cylinder 74 are smooth to permit the rotation at the respective faces of the fuel headers, and inlet valves and exhaust valves. The face of the inlet valves directed toward the inlet face of the cylinder is flat and operates in valve closing position at the inlet face of the cylinder. The face of the exhaust valve directed toward the tube outlets carries two diametrically opposed dished-out portions 84 within valve closing ribs 85. The smooth faces of ribs 85 rotate in valve closing position with respect to the exhaust face of cylinder 74. From the point of view of being as effective as possible as valves, both the inlet and exhaust valve closing faces may rub against the inlet and exhaust faces of the cylinder, but the engine of my invention will operate with only a small loss of efficiency without actual rubbing contact. There is an optimum between the advantagesof rubbing contact with the disadvantage of friction on the one hand and on the other hand the advantage of some spacing involving no friction and the disadvantage of some loss of gas pressure at the valve closing space.

In the arrangement shown, the diameter of the tubes decreases with the distance from the center in order that there will be the same number of tubes around any circle of tubes. The number of tubes is 32 for each of the six circles of tubes. Since there are in effect two engines for each 180 of the cylinder, there are 16 tubes for the half of a circle for each engine, that is, a .cycle of operation takes place in a half circle of 16 tubes.

In order to equalize the moment of thrust about the center line of the engine passing through central hollow shaft 23, this particular engine in accordance with the invention is made up of two engines 180 apart, each having a set of inlet valves and exhaust valves and group of three fuel injection orifices. At any particular instant thrust is equally developed in any group of tubes lying along the same diameters so that the moment of thrust about the center line is balanced. Although two diametrically opposed engines are preferred to avoid lack of balance, an engine may be made in accordance with the invention having only a single group or three or more groups of inlet valve, exhaust valve and fuel headers.

It is an important feature of this invention that an entirely new principle is used in the operation of the engine of this invention. In order to explain this principle, the method and that which takes place in the combustion tubes, the combustion cycle for a single half circle of sixteen tubes will be described in detail. This is also representative of the cycle for each single tube. The events or conditions occurring at any instant with respect to and in a series of sixteen tubes (that is, a cycle of tubes) are illustrated in Fig. 5.

In this figure are shown a series of sixteen tubes as taken on the line 55 of Fig. 4 representing a cycle of events and conditions throughout a combustion cycle of a series of tubes on a particular half circle. The combustion tubes of the series here shown are designated serially with numerals 101 to 116 inclusive. Fuel is supplied by headers 31, 32 and 33 and air enters the inlet openings of the tubes around the headers as indicated by arrows 52. As here shown the inlet valve 25 is just closing the inlet of tube 107 and the inlets of tubes 108 to 116 are closed. Exhaust valve 13 is just beginning to close the outlet of tube and closes the outlets of tubes 106 to 111. Exhaust of gases from the outlet of the tube is indicated by the arrows 55. Within that portion of exhaust valve 13 facing the outlet end of the tubes is a concave or dished-out portion 34 providing a communicating passage between the outlet of a group of six juxtaposed tubes, 106 to 111, so that a portion of the detonation from some of the tubes is transferred to tubes just about to be detonated, that is, from tubes .109 to 111 to tubes 106 to 107 to cause a normal shock wave to travel from the outlet end toward the inlet end of the tubes, which, upon impingement against the closing face of inlet valve 25, initiates a detonation wave within a tube.

In order to examine the events and conditions taking place within this series of sixteen tubes thus representing a cycle for the purpose of explanation, reference is first made to tube 101 as shown at the top of Fig. 5, where, as shown by cross-hatched portion 57, a mixture of fuel and air is entering the inlet end of the tube while residual exhaust gases from a prior detonation, shown in the cross-hatched portion 58, are leaving the tube drawing the fuel-air mixture into the tube. In the next tubes 102, 103 and 104 there is continued the advance of the fuel and air mixture 57 and exhaust of residual exhaust gases 58 out the tubes. In tube 105 the mixture of fuel and air 57 is almost to the outlet end of the tube, and, in anticipation of the tube being filled with fuel-air mixture, the exhaust valve 13 is just beginning to close the outlet end. .The closure of the exhaust end places an obstacle in the path of the high velocity gases which forms a shock wave travelling toward the inlet end of the tube, shown by the cross-hatched portion 59. This shock wave is substantially augmented in tubes 106 and 107 by the introduction into the outlet end of high temperature exhaust gases at high pressure, shown by cross-hatched portion 60, produced by the detonation wave from tubes 109, and 11.1, especially 110 and 111. (As explained below, detonation has started in tube 109 and has progressed to the outlet end of tubes 110 and 111). The augmented shock wave in tube 106 has progressed further toward the inlet end of the tube, as shown by the crosshatched portion 59, and in tube 107 high temperature gases at high pressure from the detonation of later tubes has progressed toward the inlet end of the tube, as shown by the cross-hatched portion 60, and the further augmented shock wave, as shown at cross-hatched portion 59, has almost reached the inlet end of this tube. In anticipation of the shock wave reaching the inlet end, inlet valve 25 is beginning to close the inlet of tube 107. In tube 108, the high pressure high temperature gases, as shown by the cross-hatched portion 60, have progressed further toward the inlet end of the tube, and the shock wave, as shown by cross-hatched portion 59, is impinging against the inlet valve 25. This impingement creates a shock Zone of very high pressure and temperature and thus initiates a detonation which is shown in tube 109 as the cross-hatched portion 61, which progresses at very high speed from the inlet valve toward the outlet end of the tube and starts to force the gases as shown at 60 out the end of tube 109. As pointed out above, the initial portion of the detonation wave from tubes 109, 110 and 111 is used to augment the shock wave which in turn initiates detonation as described above. The outlet ends of tubes 112 to 116 are open, and the gases at high temperature and pressure in these tubes, produced by the detonation, blow out the outlet ends and provide a thrust against the inlet valve. This thrust is the desired force of the engine which is used in driving a vehicle or object.

As here shown, the exhaust valve, and particularly the dished-out portion which provides the communication for the outlets of the group of tubescovered by the exhaust valve, is opposite the front closing portion of the inlet.

valve, along the axis of cylinder 74. The dished-out portion of the outlet valve is preferably opposite and embraces the front closing edge 56 of the inlet valve '25 so that the gases exhausting from the beginning of detonation in a tube or tubes are turned back into tubes ready and just about to be detonated The most important wave to travel from the outlet to inlet end of a tube taking into account the speed of rotation of the valves,

is preferred, the engine will operate even though these two front edges are substantially opposite one another.

Thus, the sudden stopping of theflow of the high velocity gas molecules at the exhaust end of a tube by the closing of the exhaust valve starts a shock wave which travels upstream from the outlet to the inlet end of the tube, retarding the movement of and compressing the fuel air mixture moving within the tube from the inlet to the outlet end. Almost immediately after the closing of the exhaust valve the dished-out port-ion thereof transfers to theoutlet end of the tube gases at high temperature and high pressure from previous detonation and the inflow of these high temperature and high pressure gases into the outlet end of the tube forms another or augmented shock wave which also travels upstream and catches up with and substantially increases the original shock wave. The resulting very strong shock wave which is thus formed has a very high pressure ratio of the order of magnitude of about 4 or 5 as it arrives at the inlet end of the tube about to impinge on the inlet face of the valve. When the inlet valve closes in front of this shock wave, this very strong shock wave impinges on and is reflected by the face of the inlet valve, raising the pressure and temperature at this face to a very high value and thus igniting -the fuel air mixture and initiating and forming a detonation wave which travels at an exceedingly high velocity through the whole fuel air mixture from the inlet to the outlet end of the tube. Such a detonation wave progressing from the inlet toward'the outlet end of the tube is shown by cross-hatched portion 61 in tube 109, and in tube 110 this detonation wave is shown as having traveled the whole length of the tube and high temperature and high pressure gases are passing out of the outlet of tube 110 into the dished out portion 84 of the exhaust valve. In tube 111, the condition of'tube 110 is continuing with the exhaust valve. just about to open. In the following tubes 1-12 to 116, inclusive, the high pressure and high temperature gases created by the detonation wave are blowing out to the atmosphere creating a thrust against the inlet valve 25. These gases in leaving the outlet end of the tube acquire a high velocity and in tube 101, for example,.toward the end of the exhaust of the high temperature and high pressure gases resulting from detonation produce low pressure within the tube and cause a suction in the inlet end to draw fuel-air mixture within the tube. In will thus be seen that as soon as the exhaust valve 13 opens the outlet end of a tube the expulsion of the gases from the outlet end provides a thrust against the inlet valve which is closing the inlet end of the tube.

In the showing of Fig. 5 this will be the case f or the tubes 112 to;116.

This thrust on the inlet valve is applied against a thrust bearing preferably having two races of ball bear in'gs 62 and 63. In the thrust bearing the thrust is transmitted to six struts 64, which are in turn fixed to the casing 3. The casing of the engine may be then affixed to any vehicle or object which is to be moved as by lugs 65. Other'lug s '66 may be 'used for additional stability if desired. i

For the purpose of starting the engine of this invention, spark plugs 127 and 128 are provided in the opposite portions of the exhaust valve extending into the dishedout space 84 of each portion. To start the engine a current of air sufficient to turn the windmill blades 49 and thus the inlet valve with fuel headers and exhaust valve is applied to the front end of the casing 3, as by means of a blower, and the two spark plugs are caused to spark while fuel in introduced through the fuel headers and orifices 34. Under these conditions with the spark ignition on, the valves and fuel headers are turned by the applied air current for asulficient length of time until combustion is started in the tubes, which, after a period of time, of the order of about a minute or few minutes, increases to the point where a shock wave is strong enough to initiate detonation in the tubes, after which the engine will continue to run'without the blower and without the spark, because, as pointed out above, the operating engine sucks air through the front against the Windmill blades 49 to turn them and the valve assembly. It will be understood that the spark plugs here shown are used only for starting the engine and not during operation after starting.

In the operation of the engine described above at conditions 'of probable maximum temperature of about 3500" F. of the detonation gases, the tube walls will prob ably reach a temperature, particularly at the outlet end thereof, of around 3,000,F., and, accordingly, it will be desirable to make these tubes of such material as will stand such temperature. For this purpose, these tubes may be made of graphite, the inside of which is coated with molybdenum disilicide or silicon carbide, or of a ceramic such as stabilized zirconium oxide. In addition to the graphite and zirconium oxide ceramic mentioned above, other ceramics may be used such as zirconium boride and silicon carbide where the maximum tube wall temperature is not greater than about 2400 F. With heat exchange cooling as shown, the exhaust valve may be maintained at a temperature of around 1800 F., and, hence a stainless steel may be used. The inlet valve may be made of stainless steel, because it does not get as hot as the exhaust valve and will be maintained at a sufficiently low temperature.

It will be understood that other fuels which can be detonated in addition to the jet turbine fuel may be used in the engine of the invention, particularly including ethylene, acetylene or other similar hydrocarbons.

As used herein, detonation, or detonation wave, is a shock wave sustained by the energy of the chemical reactioninvolved in the combustion of the gaseous fuelair mixture in the highly compressed explosive mixture travelling close behind the wave front of the shock wave. Detonation is known in the art and is described in the literature'as,- for example, in the book entitled Combustion, Flames and Explosions of Gases by Bernard Lewis and Guenther von Elbe, published by Academic Press, Inc. (1951), particularly at pages 226, 227 and chapter XI, pp. 579-628, to which book reference is made for a full description of detonation. Als0,-as used herein, shock wave is a term known in the art. It is likewise described in the literature in the reference given above, particularly at pages 590-595, and also, as another example, in the book entitled High-Speed Aerodynamics by William F. Hilton, published by Longmans, Green and 1 1 Co., particularly at pages 19-21, to which book reference is also made.

It will be understood that the specific embodiments and examples given above are for the purpose of illustrating the invention and the invention includes other modifications within the scope of the following claims.

I claim:

1. In a jet engine device for producing thrust by detonation of fuel, the combination comprising: a cylinder having two end walls carrying a set of combustion tubes within said cylinder open at the ends and extending within said cylinder from one end wall to the other, said set of tubes being symmetrically arranged in concentric circles about the center of said cylinder equally spaced from one another on each circle with the inside diameters of said tubes being larger with greater distance from the center of said cylinder and the inside diameters subtending the same angle from the center of said cylinder; inlet valve means and fuel supply means each having two diametrically opposed symmetrical portions and rotatable about the center line of said cylinder and movable over and at the inlet face of one of said end walls to open and close the inlet openings of said tubes and to supply fuel thereto respectively; and outlet valve means having two diametrically opposed symmetricalportions rotatable about the center line of said cylinder and movable over and at'the face of the outlet of said end walls to open and close the outlet openings of said tubes, each portion of said outlet valve means extending over a group of at least two tubes of each circle and having means for providing a passage for gases from the open end of one tube of said group to the open end of another tube of said group, the initial closing portion of each portion of said inlet valve and said outlet valve extending in a straight line from the axis of rotation, said inlet valve means and said outlet valve means being rotatable at the same rotatable speed with the initial closing portion of said outlet valve somewhat in advance of the initial closing portion of said inlet valve.

2. A jet engine as defined in claim 1, having means for passing fuel in heat exchange with said outlet valve means to cool said means and to preheat said fuel.

3. A jet engine as defined in claim 1, having means for passing said fuel in heat exchange with the outside of said cylinder, with said outlet valve means, and with said inlet valve means to cool said cylinder and valve means and to preheat said fuel.

4. In a jet engine for producing thrust by detonation of fuel, the combination comprising a cylinder having a front and back end wall carrying a set of combustion tubes within said cylinder open at the ends and extending within said cylinder from one end wall to the other, said set of tubes being symmetrically arranged in six concentric circles about the center of said cylinder with thirty-two tubes equally spaced from one another on each circle with the inside diameters of said tubes being larger with greater distance from the center of said cylinder and the inside diameter subtending the same angle from the center of said cylinder; a shaft extending through the center of said cylinder from the front to back thereof having affixed to the front end thereof inlet valve means and fuel supply means each having two diametrically opposed symmetrical portions rotatable with said shaft about the center line of said cylinder and movable over and at the inlet face of one of said end walls to open 12 and close the inlet openings of said tubes and to supply fuel thereto, the diametrically opposed symmetrical portions of said inlet valve means comprising two sectors of a'circle each covering a group of inlet openings of said' tubes of about nine tubes of each circle; outlet valve means having two diametrically opposed symmetrical portions fixed to the end of said shaft and rotatable therewith about the center line of said cylinder and movable over and at the face of the outlet of said end walls to open and close the outlet openings of said tubes, each portion of said outlet valve means comprising a sector of a circle extending over a group of about six tubes of each circle and having means for providing a passage for gases between the open ends of said six tubes, said inlet valve means and said outlet valve means being so arranged on said shaft with respect to one another that the outlet valve sectors close the outlet of said tubes about two tubes in advance of the closing of the inlet end of said tubes by the inlet sectors and the outlet sectors opening the outlet ends of said tube about five tubes ahead of the opening of the inlet ends of said tubes by the inlet sectors; and means for rotating said shaft, inlet valve means and outlet valve means.

5. A device as defined in claim 4, having a cylindrical housing surrounding said cylinder and extending backward thereof over said outlet valve means and forward thereof over and beyond said inlet valve means; and means within said housing ahead of said inlet valve means for rotating said shaft and said inlet and outlet valve means by energy obtained from air moving into and through the front portion of said housing.

6. A device as defined in claim 5, in which said means for rotating said shaft comprises a windmill afiixed to the front end of said shaft.

7. A device as defined in claim 6, in which said windmill carries blades extending into the air stream within said housing and in which said device also has means for adjusting the speed of rotation of said windmill comprising a set of blades in front of the blades of said windmill adjustable to regulate the angle of impingement of said air current on said windmill blades.

8. A device as defined in claim 7, in which said device carries a set of blades between said windmill blades and said inlet valve means for directing the air current directly into the inlets of said tubes.

9. A device as defined in claim 8, having means for simultaneously adjusting the pitch of said set of blades in front of the windmill blades and the pitch of said set of blades behind the windmill blades.

10. A device as defined in claim 5, having means for,

adjusting the speed of rotation of said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,980,266 Goddard Nov. 13, 1934 2,515,644 Goddard July 18, 1950 2,525,782 Dunbar Oct. 17, 1950 2,632,294 Wall Mar. 24, 1953 2,633,699 Goddard Apr. 7, 1953 2,633,703 Tenney et al Apr. 7, 1953 FOREIGN PATENTS 844,442 France Apr. 24, 1939 176,838 Great Britain Mar. 6, 1922 wew res-His. 

